深厚软弱地层地下连续墙槽壁稳定性分析

Stability Analysis of Trench of Diaphragm Wall in Deep Water-Soaked Soft Stratum

考虑土体的分层特征,假定槽壁破坏体为具有倾斜滑动面的三维楔形体,基于土体极限平衡原理推导了深厚软弱地层中地下连续墙槽壁的稳定安全系数表达式。提出以强度等效原理计算槽壁加固后复合土体抗剪强度指标的方法,进而推导了土体加固后槽壁的稳定安全系数表达式。引用算例验证了槽壁稳定安全系数的有效性并结合工程实例对深厚软弱地层中槽壁的稳定性影响因素进行了详细分析。结果表明,软弱土层的槽壁失稳现象更容易出现在浅层部位,加固后槽壁失稳可能出现在深层部位。减小槽段施工长度、增加泥浆比重和液面高度、增大加固体厚度和强度、降低地面超载和地下水位等措施均有利于富水软弱地层中地下连续墙槽壁的稳定性。

In order to analyze stability of trench of diaphragm wall in deep water-soaked soft stratum,the failure model of trench was assumed to be a three-dimensional wedge shape with slope sliding surface in consideration of the soil anisotropy.Stability factor calculation formula of trench of diaphragm wall was deduced based on limit equilibrium theory,shearing strength parameters of composite soil were calculated with equivalent shear strength,then stability factor calculation formula of trench was deduced after consolidating the soil.Combined with the example,different results were derived by use of the existing computing method and the method.The research results show that the effect of different factors on the stability of trench in deep water-soaked soft stratum were discussed according to the calculation formula.Instability of slurry wall in deep water-soaked soft stratum is more likely to occur in shallow ground before reinforcement,and potential to occur in deep ground after reinforcement.Some precautionary construction measures,including decreasing length of grooves,increasing unit weight of slurry appropriately and liquid level,increasing strength of cement-soil and reinforced width,reducing ground overloading and underground water level,are beneficial stability of trench of diaphragm wall in deep water-soaked soft stratum.